I just sold my moderately bombed (Hot flip chip, turbo upgrades, tranny mods, etc.) 00 Ford CC 4x4 PSD Dually and when pulling our 30" livestock trailer up and down hills in Iowa (10-12K) wouldn't downshift or lug that bad. It's just the rest of the truck that was falling apart. It had 235 85 R16s and 3.73s.

Now these new Dodge's got bigger rims and tires, so is that factor coupled with the 3.73 rear end actually going to give me a taller final gear than my Ford did even though same rear end? Or is tranny built with lower gears to accomodate the large tires? The stock Cummins ought to be able to hang with or beat my PSD, but I want to make sure I get the right rear end in this thing. 4.10s mileage sucks and motor is always wound up, but since these have big tires/rims maybe not as bad? I would maybe like to upgrade to 285s or something of that nature as well, can this be done at the dealer? (I.E. into cost of truck on loan?)

Basically I dont want to be downshifting and lugging with 10K behind me but I dont want to be running huge RPMs and sucking $2 diesel. Which do you recommend? Terrain is mostly flat here but hit I80 west pulling to Iowa/Ne/SD a lot/

Thanks!

Oh and for all you guys moaning and groaning about your "horrible" mileage with your 600s--My PSD even when driven like a blue hair would struggle to get 13, about 9 pulling the trailer.!

 

Over all the diameter of the tires you had on your Ford and the Dodge tires are about the same. The Ford had 235/85/16 verses 265/70/17. I have 4.10 ratio on my Dodge and went with 315/70/17 to get about 34.5 inch diameter tires. I think the orginal tires were about 31 inch diameter. I like the 4.10 gearing because you have more flexability with tire sizes. With the higher ratios, your gearing gets to high if you want larger tires. I had a ford with 3.73 rear and went with 36 inch tires. The gearing was to tall for most things. I haven't gotten the poor mileage others have talked about. 15 MPH on the first full tank of gas. It had about 50 miles on the truck, I filled it up to the top of the fill tube and drove it 200 miles. The gauge read 3/4 full when I got back. I again filled to the top of the fill tube and had used 13 gallons of fuel. Just over 15 MPG. There was 15 miles of second and third gear driving on a unimproved dirt road at 10 to 20 MPH. The rest was 70 MPH highway driving. No virbrations.

 

Thanks for the info--I guess I didnt realize that the tires would be roughly the same height. If I did go to 315s (Although the load range D kinda scares me, nothing like a blowout at 70 mph with a load of cattle behind you) then the 4.10s would basically be like the same ratio as 3.73s with stock tires. Any idea if dealer would do 315s and how much more it would cost?

 

When I received my truck, I hot footed up to my local tire store and traded the tires for the 315's He gave me a reasonable trade-in for the new tires off my truck. If I was hauling very heavy loads, I'd look to stay with the E rated tires. I have a couple of hundred extra pounds hanging in front of my bumper with my winch and carrier. I just run 55 to 60 pounds of air in the front tires. 5 or 6 hundred extra pounds in back, but a light trailer. My guess is that the weight I have in back is about the same as your toung weight if it's not a goose neck trailer. If this is true, the D rated tires should be OK. If you have a heavy goose neck trailer, I would stay with the D rated tires.

 

My trailer is indeed a goosneck--empty weight of 5600# and generally runs 10-12K loaded. The Ds would be pushing my luck I suppose.